Method and device for supplying printing ink to and carrying it off from a doctor blade device of the inking system of a rotary printing press and/or for cleaning the doctor blade device

ABSTRACT

The invention relates to a method and a device for supplying printing ink to and carrying it off from a doctor blade device of the inking system of a rotary printing press. Said device comprises a doctor blade support provided with a linearly extending groove and with doctor blades that can be put against an inking roller or screen roller, said blades delimiting together with the inking roller and the groove an inking chamber. The device further comprises conduits and motor-driven pump devices for supplying ink to and carrying it off from the inking chamber. The motors used are preadjusted in terms of their parameters and are not modifiable during operation. If necessary, a portion of the ink from the flow of ink supplied to the doctor blade device can be carried off and/or a portion of the ink from the flow of ink carried off from the doctor blade device can be returned to the supply conduit.

The invention concerns a process and a device for supplying printing inkto and educing printing ink from a squeegee device of an inking systemon a rotary printing press and for cleaning the squeegee device, whichcomprises a squeegee blade carrier, provided with a longitudinallyrunning trough, with squeegee blades that are adjustable on a forminking roller that, together with the form inking roller and the trough,delimit an ink chamber, and comprise lines and pumping devices poweredby motors for supplying and educing the ink or the cleaning agent intoand out of the ink chamber.

A device of this type is known from the German patent DE 195 48 535 C2with which residual ink can be removed not only from the ink chamber ofthe squeegee device, but also from the supply and evacuation lines whilereducing the amount of dissolving agent used for cleaning, in that theink from the ink chamber is pumped back into an ink tank via theevacuating lines, in that the dissolving agent is subsequently pumpedout of a dissolving agent tank via the supply lines into the ink chamberand is channeled via the evacuating lines into the ink tank for apredetermined amount of time, in that admission into the ink tank issubsequently stopped and in that the dissolving agent still soiled bythe ink is pumped into a waste tank for a predetermined amount of time,in that the supply flow of dissolving agent from the dissolving agenttank is subsequently interrupted and in that the dissolving agent stillpresent in the circulation system is pumped into the waste tank as well,in that fresh dissolving agent is subsequently pumped via the supplylines and educing lines in a closed cleaning circuit for a predeterminedamount of time and in that finally, the dissolving agent that was fedthrough the closed cleaning circuit is channeled into the waste tank.The known device is elaborate to the extent that an ink pump, adissolving agent pump and two mutually connected pumps are provided forpumping ink and dissolving agent back into the ink tank or into thewaste tank. The use of several pumps creates high procurement costs onthe one hand.

On the other hand, it must be taken under consideration in the case ofthe known device that during the circulation of the ink under printingoperations, a larger volume must be fed back into the ink tank than isbeing pumped into it, since the ink in the ink chamber becomes enrichedwith air. As a consequence of this, the evacuating pump must pump alarger volume than the delivery pump. This volumetric pumping ratio mustbe permanently monitored and readjusted manually when required.

The task of the present invention is therefore to propose a process anda device of the type initially indicated, which can manage with a numberof pumps for circulating the ink and/or for cleaning with a dissolvingagent or cleaning agent and for which it is not required to readjust thevolumetric pumping ratio.

This task is resolved in accordance with the invention by thecharacteristics of patent claim 1.

Furthermore, this task is also resolved for a device of the typeinitially indicated in that two pumping devices are provided that arepreset in their parameters, and that, when required, a portion of theink from the ink stream supplied to the squeegee device is channeled offand/or a portion of the ink from the ink stream led away from thesqueegee device is rechanneled to the squeegee device.

The underlying task of the invention is also resolved for a device ofthe type initially indicated in that two pumping devices are provided,of which the first pumping device, via regulating valves, suctions offink or cleaning agent from an ink reservoir or from a cleaning agentreservoir, and pumps it into the ink chamber, and of which the secondpumping device pumps an ink-air mixture from the ink chamber into theink reservoir, or pumps cleaning agent or cleaning agent containing inkinto a waste reservoir containing used cleaning agent, and that, via aregulating valve, the supply line stands in connection with a lineleading to the ink reservoir, in which an adjustable throttle valve orthroughflow regulating valve is arranged.

As compared to the known device, the process in accordance with theinvention and the device in accordance with the invention make itpossible to circulate the ink during printing operations and to cleanthe squeegee device with only two pumps. In order to be able to providetwo pumping capacity devices according to the invention with anestablished efficiency ratio, then in accordance with the invention, atleast one bypass must be provided that comprises a line branching outfrom the feed lines. Purposefully, the outbranching line channels theink directly back into the ink tank.

Given the case, that the vacuum pump has a greater pumping capacity thanthe priming pump, in addition to the first bypass or in place of thefirst bypass, it is advantageous to provide a line that leads from thepressure side of the vacuum pump to the supply line of the squeegeechamber.

Advantageously, the bypass line branching out from the feed line and/orthe line leading from the pressure side of the eduction pump to thesupply side of the squeegee chamber are each respectively equipped witha cutout valve and/or with a throughflow regulating valve. Thethroughflow regulating valves are empirically adjusted in such a mannerthat, for example, a portion of the ink supplied by the priming pump isimmediately recirculated into the ink tank or that the ink drawn off bythe vacuum pump is made available anew to the supply side of thesqueegee chamber. In this manner, it is generally ensured duringprinting operations that the eduction volumes and the feed volumes, andthe volumes supplied to and drawn off from the ink chamber are aboutequal, while taking under consideration the circumstance that, in theink chamber, the ink becomes enriched with air.

It is especially advantageous if the fill level of the ink in thesqueegee chamber is monitored by a sensor and, in the event that thespecified fill levels are exceeded or not attained, the throttle valvesor the throughflow regulating valves are set in such a manner, via aregulated circuit, so that the fill level will again resume its statuswithin the specified limits.

According to an especially preferred embodiment of the invention, it isprovided that the two pumping devices comprise two chambers from adouble diaphragm pump with only one drive shaft. Such double diaphragmpumps with separate chambers, of which the one can assume delivery andthe other can assume recirculation, are sold, for example, by theALMATEC Maschinenbau [machine building] GmbH company, in D-47475Kamp-Lintfort. Advantageously, the two chambers of the double diaphragmpump have the same volumetric pumping capacity.

Furthermore, the feed line can be provided with a line leading to thewaste tank, which features a valve and a throttle valve or a throughflowregulating valve. This line is a bypass line, through which cleaningagent pumped into the squeegee chamber during cleaning of the squeegeedevice can be recirculated, in order to take the circumstance intoaccount, that during the cleaning process, the cleaning agent alsobecomes enriched with air so that, during the cleaning process, thevolume that was recirculated out of the squeegee chamber is greater thanthe volume that was pumped in. Since the cleaning agent that wasrecirculated via the bypass line is not soiled or barely soiled, it canbe advantageous to let the bypass line flow into the tank for cleancleaning agent.

Exemplary embodiments of the invention shall be more closely detailed inthe following by the use of drawings, in which the device in accordancewith the invention for supplying and educing printing ink to and from asqueegee device of an inking system on a rotary printing press and forcleaning the squeegee device is schematically represented.

The individual figures show:

FIG. 1 Schematic representation of the device with bypass devices on thesupply side

FIG. 2 Schematic representation of the device with a bypass device onthe eduction side

In FIG. 1, the device shown in accordance with the invention is designedfor the case in which the pumping capacity of the pump chamber 3 isequal or greater than the pumping capacity of the pump chamber 4. Intothe central section of the ink chamber, which is a component part of thesqueegee device 1, a feed line 2 flows in that is connected to thedelivery side of a pump chamber 3 of the double diaphragm pump 3, 4. Thesuction side of the pump chamber 3 of the double diaphragm pump 3, 4can, via the line shutoff valves or the cutout valves 5, 6, either beconnected to the suction line 7, which flows into the ink tank 8, orconnected to the suction line 9, which flows into the tank 10 for cleancleaning agent.

Connected to the feed line 2, via the line shutoff valve or the cutoutvalve 11, is a line 12, in which an adjustable throttle valve orthroughflow regulating valve 13 is arranged. A throttle valve 25 canalso be provided in the feed line 2.

The suction side of the second pump chamber 4 of the double diaphragmpump 3, 4 is connected to the recirculation lines 14, 15, which areconnected on the sides of the ink chamber of the squeegee device 1. Thepressure side of the second pump chamber 4 of the double diaphragm pump3, 4 is connected to a line 16, which, via line shutoff valves or cutoutvalves 17, 18, can be connected to a line 19 leading to the ink tank 8,or can be connected to a line 21 that flows into the waste tank 20 forused cleaning agent.

Another line 24 can be connected, via the line shutoff valve or thecutout valve 23, to the feed line 2, in which an adjustable throttlevalve or throughflow regulating valve 25 is arranged and which flowsinto the waste tank 20.

Upon starting the printing operation and during the printing operation,valve 5 finds itself closed in its basic state. Via the suction line 7and via valve 6, which is open in its basic state, ink is delivered intothe ink chamber of the squeegee device 1 through the pump chamber 3 ofthe double diaphragm pump 3, 4 and through the feed line 2. During theprinting operation, printing ink or printing ink enriched with air ispumped back into the ink tank 8 via the recirculation lines 14, 15 andvia the second pump chamber 4 of the double diaphragm pump 3, 4, via theline 16 and the valve 17, with valve 18 being closed. Since the pumpchamber 3 of the double diaphragm pump 3, 4 has an equal or greatervolumetric capacity than pump chamber 4, and the recirculated ink, inspite of the reduction in ink due to the material printed, exhibits agreater volume due to its enrichment with air than does the inkdelivered through the feed line 2, a partial quantity of the printingink is pumped back, during the printing operation, into the ink tank 8with valve 11 open and through line 12 and through the throttle valve13, so that the pumping ratio between the two pump chambers 3, 4 matchesthe volumes pumped.

When cleaning the ink chamber and the lines channeling the printing ink,the valve 6 is closed, and while valve 5 is open, via the line 9, cleancleaning agent is suctioned from tank 10 and is channeled into the inkchamber via the feed line 2, with valve 11 closed. During this cleaningprocess, initially, the ink that can still be displaced by the cleaningagent via valve 18 and via line 19, with valve 18 closed, is channeledinto the ink tank 8. However, as soon as the ink is diluted by thesolvent, valve 17 is closed and valve 18 is opened, and the cleaningagent or solvent rendered impure with the ink is channeled into thewaste tank 20 via line 21. Since the cleaning agent also becomesenriched with air in the ink chamber during the cleaning process, a line24 can be connected to the feed line 2 via valve 23, in which theadjustable throttle and throughflow regulating valve 25 is arranged andwhich flows into the waste tank 20. As soon as this occurs, cleaningagent can be channeled into the waste tank via this line 24 in order totake the circumstance into account that the cleaning agent that isrecirculated through lines 14, 15 is enriched with air. To the extentthat clean cleaning agent could be branched out from the feed line 2,line 24 could also be made to flow into the tank 10 for clean cleaningagent.

FIG. 2 shows another preferred form of embodiment of the invention,wherein the representation of the cleaning agent tank and of thecleaning agent lines has been omitted for reasons of gaining a clearoverview. In the event that pump chamber 4 of the double diaphragm pump3, 4 should display a volumetric capacity that is substantially greaterthan pump chamber 3, a portion of the ink pumped out from feed line 2must be led back through the recirculation line 27. A throttle valve ora throughflow regulating valve 29 is provided for regulating the returnflow. Furthermore, another cutout valve 28 can be provided that isclosed when the ink is to be pumped out of the ink chamber.

Of course, the bypass 27, 28, 29 represented in FIG. 2 can also beintegrated into the device in accordance with FIG. 1.

1: Process for supplying printing ink to and educing printing ink from asqueegee device (1) of an inking system on a rotary printing press,which comprises a squeegee blade carrier, provided with a longitudinallyrunning trough, with squeegee blades that are adjustable on a forminking roller or on an anilox roller, which, together with the forminking roller and the trough, delimit an ink chamber, and comprise linesand pumping devices (3, 4) powered by motors for supplying and educingthe ink into and out of the ink chamber, thus characterized that motorsare used whose parameters have been preset and which do not changeduring operation of the motors and that, when required, a portion of theink from the ink stream supplied to the squeegee device is channeled offand/or a portion of the ink from the ink stream led away from thesqueegee device is rechanneled to the feed line (2). 2: Device forimplementing the process in accordance with claim 1, thus characterizedthat at least one line (12) branches off from the feed line (2). 3:Device in accordance with claim 2, thus characterized that the line (12)leads back to the ink tank (8). 4: Device for implementing the processin accordance with claim 1, thus characterized that at least one line(27) leads from the pressure side of the vacuum pump (4) to the feedline (2) of the squeegee device (1). 5: Device in accordance with claim2, thus characterized that a throughflow regulating valve (13, 26, 29)and/or a cutout valve (11, 28) is arranged in at least one line (2, 12,27). 6: Device in accordance with claim 5, thus characterized that, formonitoring the quantity of ink present in the squeegee device (1), asensor is provided whose signals are processed through a closed loopcontrol circuit that regulates the throughflow regulating valve (13, 26,29) in such a manner that the quantity of ink circulating in thesqueegee device (1) is always maintained within specified limits. 7:Device for implementing the process in accordance with claim 1, thuscharacterized that the two pumping devices (3, 4) comprise two chambersof a double diaphragm pump with only one drive shaft.